Identifying spam amongst legitimate e¬mails is made trickier because spammers commonly use a technique known as spoofing to retain their anonymity. Spoofing makes it appear that an e-mail
has been sent from a completely different e-mail address to the one it has really been sent from. The spammer changes the information

attached to the e-mail- called the header - that shows where it originated from to make it look like the e-mail has been sent by someone else. Sometimes this e-mail address is non-existent, but sometimes the spammer will have guessed at an email address that is actually in use. So the first the real owner of the e-mail address knows about it is when they receive irate, and often not particularly polite, messages from strangers demanding they stop spamming them.

Be aware that it's not just the name at the start of an e-mail address - the Joe.Bloggs bit - that can be spoofed. Looking for a credible or recognised domain ¬the bit after the - in the From: line of an e-mail isn't enough to guarantee its authenticity. Spammers are also able to spoof domains, which is why in a phishing scam, the fraudster can pose as a company the recipient does business with.

However, there are various hallmarks of spam e¬mails that can be used collectively to help identify spam. In unsophisticated cases, the e-mail address in the From: field is often a bit of a mess, containing an em ail address that is often just a random string of letters and numbers followed by a webmail domain. For instance, Let's face it, that wouldn't be your first choice when signing up to an email service. Also look out for e-mail addresses that appear to have been sent from different e-mail addresses, but have identical subject lines or ones that make no sense.

While the majority of e-mail programs have built-in spam blockers, there will be the odd piece of digital junk that repeatedly breaches security and makes it into your inbox. In this case, the most effective means of prevention is to block e-mails arriving from a specific sender or domain, also called a fixed address. To do this in Outlook Express, click on a message from the sender that you want to block. Then, in the Message menu, click Block Sender. Now any e-mail you receive from this sender will automatically find itself in your Deleted Items folder.

Adding names to the Block Sender list in Outlook produces the same result, but requires a slightly different process. Click Options within the Tools menu and, on the Preferences tab, under E-mail.click Junk E-mail. Now click the Block Sender tab and then Add.

Within the box 'Enter an e-mail address or Internet domain name to be added to the list', type in the offending e-mail address, then click OK. Alternatively, right-click the unwelcome email and click Junk E-mail to add the sender to the Block Sender List.